There are 2 US Post Offices in Walthall County serving a total of 15,038 residents equating to 7,519 residents per post office. It's estimated that approximately 24,002 packages are handled across the 2 county post offices annually. Walthall County is a county located in the U.S. state of Mississippi. As of the 2010 census, the population was 15,443. Its county seat is Tylertown. The county is named after Civil War general and Mississippi Senator Edward C. Walthall.